Patient specific surgical guide locator and mount

ABSTRACT

A resection guide locator includes a bone engagement portion with surfaces that are complementary to the surface topographies of a bone to be resected during surgery. A housing includes a socket defined by a resilient annular wall that is sized and arranged so to accept a resection guide by press-fit to thereby position and hold the resection guide within the socket. The resection guide is maintained in a predetermined, preferred position while the surfaces are releasably locked in position on the bone. A method is disclosed for forming and using the resection guide locator.

This application is related to, and claims the benefit of U.S.provisional patent application Ser. No. 61/154,845, filed Feb. 24, 2009,and entitled Patient Specific Surgical Guide Mount.

FIELD OF THE INVENTION

The present invention generally relates to surgical guides, and thefixtures used to locate such guides in relation to a patient's bodyduring orthopedic procedures, such as, total knee, hip, or anklereplacement surgery, and methods for designing and using such instrumentlocators.

BACKGROUND OF THE INVENTION

Total joint (knee, hip, and ankle) replacement prostheses are known inthe art. In many instances, a specially designed jig or fixture enablesthe surgeon to make accurate and precise bone resections of the femoralsurface, the tibial surface, or both in order to accept such prostheses.The ultimate goal with any total joint prosthesis is to approximate thefunction of the natural, healthy structures that the prosthesis isreplacing. Should the prosthesis not be properly attached to the femur,tibia, ankle or foot, any misalignment could result in discomfort to thepatient, gate problems, or degradation of the prosthesis.

For example, when attaching a knee prosthesis it is desirable to orientthe prosthesis such that the pivot axis of the knee joint lies within atransverse plane that is generally oriented perpendicular to themechanical axis of the femur. The mechanical axis lies along a linewhich intersects the femoral head and the center of the ankle. In theprior art, the mechanical axis had been determined from an inspection ofa radiograph of the femur to be resected prior to, or even during thesurgery. During the actual operation, the mechanical axis was determinedby computing its valgus angle from the femoral shaft axis. It was thennecessary to manually align any cutting guide and its fixtures withrespect to the femoral shaft axis in order to achieve an optimum cut.

Often such cutting guides included a femoral intramedullary stem whichwas inserted through a pre-drilled passage way formed in theintercondylar notch and upwardly through the femur along the femoralshaft axis. The stem often included a bracket which supports a distalfemur cutting guide. The bracket included a first pin which extendedthrough the cutting guide to act as a pivot axis. A second pin wasattached to the bracket so as to extend through an arcuate slot in thecutting guide. The cutting guide included pairs of opposing slots formedalong its sides which were oriented to be perpendicular to a centralaxis of symmetry of the cutting guide. When the cutting guide waspivoted, such that the central axis of symmetry lay along the mechanicalaxis, so as to form the appropriate angle with the femoral shaft axis,the cutting guide slots were positioned to be perpendicular to themechanical axis. The cutting guide was then locked into thepredetermined angle with the femoral shaft axis.

In more recent times, computer-aided design techniques have been coupledwith advances in imaging technology to improve joint replacementprostheses and methods. For example, in U.S. Pat. No. 5,735,277, aprocess of producing an endoprosthesis for use in joint replacement isdisclosed in which a reference image for determining contour differenceson a femur and a tibia, are obtained by comparing a correctedpreoperative image of a damaged knee joint with a postoperative image.This technique is then used as the basis for preparing correspondingfemoral and tibial components of an endoprosthesis.

In U.S. Pat. No. 6,944,518, a method for making a joint prosthesis isprovided in which computed tomography, commonly known as a CAT scan (CT)data from a patient's joint is used to design a prosthesis. The CT datais downloaded into a computer aided design software in order to designat least an attachment part, and possibly a functional part, of theprosthesis. The attachment part can be used to attach or otherwiseassociate the functional part to the patient's bone.

In U.S. Pat. No. 5,370,692, a method for producing prosthetic boneimplants in which imaging technology is used to define hard tissuecharacteristics (size, shape, porosity, etc.) before a trauma occurs(“pre-trauma” file) by archival use of available imaging techniques(computed tomography, magnetic resonance imaging, or the like). Loss ofhard tissue is determined by imaging in the locale of the affectedtissue after the injury (“post-trauma” file). The physical properties ofthe customized prosthetic device are specified by comparison of thepre-trauma and post-trauma files to produce a solid model “design” file.This specification may also involve secondary manipulation of the filesto assist in surgical implantation and to compensate for anticipatedhealing process. The design file is mathematically processed to producea “sliced file” that is then used to direct a manufacturing system toconstruct a precise replica of the design file in a biocompatiblematerial to produce the implant.

In U.S. Pat. No. 5,798,924, a method for producing endoprosthesis wherea data block of a three-dimensional actual model of existing bonestructure of a patient is acquired using CT scanning. In a computer, theactual model is subtracted from the data block of an existing or CTscan-generated three-dimensional reference model. Then from thedifference, a computer-internal model for the endoprosthesis is formed.The data blocks of the actual model and reference model are convertedinto the data of a CAD free-form surface geometry.

None of the forgoing methods or devices have adequately providedsurgeons with a way to generate patient specific prostheses, surgicalinstruments, guides, and fixtures, nor have they aided in reducing thenumber or complexity of the fixtures used to locate resection guides inrelation to the patient's body during orthopedic procedures, such as,total knee, hip, or ankle replacement surgery.

SUMMARY OF THE INVENTION

The present invention provides a resection guide locator including abone engagement portion having a surface topographically complementaryto the surface contours of a bone to be resected during a surgicalprocedure. A socket is defined in a housing that is attached to theengagement portion. A resilient wall of the resection guide locatordefines the peripheral extent of said socket, and is sized and shapedfor storing energy when a resection guide is press-fit into the socket.In use during surgery, the resection guide operatively engages a portionof the wall so as to maintain the guide in position while the surface ofthe bone engagement portion is releasably locked to the bone.

In another embodiment of the invention, a resection guide locator isprovided that includes a bone engagement portion with two surfaces thatare complementary to respective separate surface topographies of a boneto be resected during surgery. A housing portion is attached to the boneengaging portion, and includes a socket defined by a resilient annularwall that is sized and arranged so to accept a resection guide bypress-fit to thereby position and hold the resection guide within thesocket. In this way, the resection guide is maintained in apredetermined, preferred position while the two surfaces are releasablylocked in position on the bone.

In a further embodiment, a resection guide locator is provided thatincludes a base sized to engage a portion of a bone to be resectedduring surgery. The base has at least one surface that istopographically complementary to the surface topography of the bone. Ahousing that is attached to the base comprises a socket defined by aresilient peripheral wall arranged for storing energy when a resectionguide is press-fit into the socket so as to operatively engage the wall.This arrangement maintains the guide in a predetermined positionrelative to the bone while the topographically complementary surface ofthe bone engagement portion is releasably locked onto the bone.

A method for forming and positioning a resection guide is also providedin which an anatomically accurate image of a bone is generated thatincludes surface topographies of the bone. The anatomically accurateimage is converted to a digital model, and a digital representation of aresection guide locator is added to the digital model so as to form acomposite digital model. Once the surface topographies complementarilymapped onto a bone engagement portion of the resection guide locatorprior to manufacturing the resection guide locator based upon thecomposite digital model so that a manufactured resection guide locatoris formed including the complementary surface topography on a boneengagement portion and a receptacle pocket sized to receive a resectionguide with a press-fit. The resection guide locator is applied to thebone such that the complementary surface topography releasably locks thebone engagement portion to a corresponding portion of the bone.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bemore fully disclosed in, or rendered obvious by, the following detaileddescription of the preferred embodiment of the invention, which is to beconsidered together with the accompanying drawings wherein like numbersrefer to like parts and further wherein:

FIG. 1 is a perspective view of femoral and tibial resection guidesmounted within resection guide locators that have been formed inaccordance with the present invention and located upon portions of afemur and a tibia, respectively;

FIG. 2 is a schematic representation of a scanned image of a human kneejoint;

FIG. 3 is a schematic representation of the scanned image of the humanknee joint shown in FIG. 2, after conversion to a computer model inaccordance with the present invention;

FIG. 4 is a schematic representation, similar to FIG. 3, showingproposed resection lines and local coordinates superpositioned upon thecomputer model of FIG. 3, in accordance with the present invention;

FIG. 5 is a schematic representation similar to FIG. 4;

FIG. 6 is a schematic representation similar to FIGS. 4 and 5, butshowing a femoral and a tibial resection guide locator representedwithin the computer model of FIG. 3 in accordance with the presentinvention;

FIG. 7 is a schematic representation similar to FIGS. 4, 5, and 6,showing a digital representation of the femoral and tibial prostheses(in cross section) superimposed within the model in accordance with thepresent invention;

FIG. 8 is a perspective view of a femoral resection guide locator formedin accordance with the present invention;

FIG. 9 is a rear perspective view of the femoral resection guide locatorshown in FIG. 8;

FIG. 10 is an elevational view of the front side of the femoralresection guide locator shown in FIG. 9;

FIG. 11 is an elevational view of the bottom of the femoral resectionguide locator shown in FIGS. 9 and 10;

FIG. 12 is a perspective view of a tibial resection guide locator formedin accordance with the present invention;

FIG. 13 is a perspective bottom view of the tibial resection guidelocator shown in FIG. 12;

FIG. 14 is a top view of the tibial resection guide locator shown inFIG. 13;

FIG. 15 is a rear elevational view of the tibial resection guide locatorshown in FIG. 14;

FIG. 16 is a perspective view of a typical tibial resection guide;

FIG. 17 is a front elevational view of the tibial resection guide shownin FIG. 16;

FIG. 18 is a side perspective view of the tibial resection guide shownin FIG. 17;

FIG. 19 is a perspective view of a femoral resection guide mountedwithin a femoral resection guide locator positioned upon the condyles ofa femur;

FIG. 20 is a perspective view of a tibial resection guide mounted withina tibial resection guide locator positioned upon the articular surfacesof a tibia;

FIG. 21 is a perspective view of tibial and talar resection guidesmounted within resection guide locators that have been formed inaccordance with the present invention and located upon portions of atibia and a talus, respectively;

FIG. 22 is a perspective view of a tibial resection guide locator formedin accordance with the present invention;

FIG. 23 is an exploded perspective view of a tibial resection guide andtibial resection guide locator formed in accordance with the presentinvention;

FIG. 24 is a perspective view of a tibial resection guide mounted withina resection guide locator that have been formed in accordance with thepresent invention and located upon the lower portion of a tibia;

FIG. 25 is a front elevational view of a tibial resection guide mountedwithin a resection guide locator that have been formed in accordancewith the present invention and located upon the distal portion of atibia;

FIG. 26 is an exploded side elevational view of a tibial resection guideand tibial resection guide locator formed in accordance with the presentinvention located upon the lower portion of a tibia;

FIG. 27 is a schematic representation of a resected distal tibiafollowing application and use of a tibial resection guide and tibialresection guide locator formed in accordance with the present invention;

FIG. 28 is a perspective view of a talar resection guide mounted withina talar resection guide locator that have been formed in accordance withthe present invention and located upon a portion of a talus;

FIG. 29 is a perspective view of a talar resection guide mounted withina talar resection guide locator formed in accordance with the presentinvention;

FIG. 30 is an exploded perspective view of a talar resection guide andtalar resection guide locator formed in accordance with the presentinvention;

FIG. 31 is a perspective view of a talar resection guide locator formedin accordance with the present invention located on a talus bone of anankle;

FIG. 32 is a front elevational view of a talar resection guide mountedwithin a resection guide locator that have been formed in accordancewith the present invention and located upon the frontal portion of atalus bone;

FIG. 33 is an exploded side elevational view of a talar resection guideand a talar resection guide locator formed in accordance with thepresent invention located upon the upper portion of a talus; and

FIG. 34 is a schematic representation of a resected talar bone followingapplication and use of a talar resection guide and talar resection guidelocator formed in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This description of preferred embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description of this invention. The drawingfigures are not necessarily to scale and certain features of theinvention may be shown exaggerated in scale or in somewhat schematicform in the interest of clarity and conciseness. In the description,relative terms such as “horizontal,” “vertical,” “up,” “down,” “top” and“bottom” as well as derivatives thereof (e.g., “horizontally,”“downwardly,” “upwardly,” etc.) should be construed to refer to theorientation as then described or as shown in the drawing figure underdiscussion. These relative terms are for convenience of description andnormally are not intended to require a particular orientation. Termsincluding “inwardly” versus “outwardly,” “longitudinal” versus “lateral”and the like are to be interpreted relative to one another or relativeto an axis of elongation, or an axis or center of rotation, asappropriate. Terms concerning attachments, coupling and the like, suchas “connected” and “interconnected,” refer to a relationship whereinstructures are secured or attached to one another either directly orindirectly through intervening structures, as well as both movable orrigid attachments or relationships, unless expressly describedotherwise. When only a single machine is illustrated, the term “machine”shall also be taken to include any collection of machines thatindividually or jointly execute a set (or multiple sets) of instructionsto perform any one or more of the methodologies discussed herein. Theterm “operatively connected” is such an attachment, coupling orconnection that allows the pertinent structures to operate as intendedby virtue of that relationship. In the claims, means-plus-functionclauses, if used, are intended to cover the structures described,suggested, or rendered obvious by the written description or drawingsfor performing the recited function, including not only structuralequivalents but also equivalent structures.

The present invention provides custom manufactured surgical instruments,guides, and fixtures that are based upon a patient's anatomy asdetermined by a computer tomography scanner (CT), magnetic resonanceimaging machine (MRI), or the like medical imaging technology. Forexample, a CT or MRI scanned image 1 or series of images may be taken ofa patient's knee 1 or ankle 1 a, including portions of the limb from thepelvis or the foot (FIGS. 2 and 3). In the case of a total kneereplacement, the CT or MRI scanned image data is then converted from,e.g., a DICOM image format, to a solid computer model 3 of the lowerlimb often including the pelvis, femur, patella, tibia, or foot todetermine implant alignment, type and sizing using specialized modelingmethods that are often embodied in computer software. Computer generatedsolid models 3 that are derived from CT or MRI scan image data 1 willoften include precise and accurate information regarding the surfacecontours surrounding the structures that have been imaged, e.g., thesurface topography of the bones or contour of fascia that have beenimaged. It will be understood that by surface topography it is meant thelocation, shape, size and distribution of surface features such asconcavities and prominences or the like.

The methods disclosed in U.S. Pat. No. 5,768,134, issued to Swaelens etal., and incorporated herein by reference, have been found to yieldadequate conversions of CT or MRI scanned image data 1 to solid computermodel 3 usable with the present invention. In some embodiments, imagesare made of a lower limb, i.e., the pelvis, femur, patella, tibia,and/or foot of a patient using a CT or MRI machine, or other digitalimage capturing and processing unit (FIGS. 2 and 3). This scanninggenerates a scanned image of the diseased knee or ankle joint, includingadjoining portions of the femur 5 and tibia 6. The image data 1 is firstprocessed in a processing unit, after which a model is generated usingthe processed digitized image data.

In accordance with the present invention, interactive processing andpreparation of the digitized image data is performed which includes themanipulation and introduction of additional extrinsic digitalinformation 8, such as, predefined reference locations 9 for componentpositioning and alignment 10 so that adjustments to the surgical site,that will require resection during surgery, may be planned and mappedonto computer model 3 (FIGS. 4 and 5). After the interactive processingof the digitized image data, it is possible to go back to original CADdata to obtain a higher resolution digital representation of the patientspecific surgical instrument, prostheses 7 a, 7 b (FIG. 7) guide, orfixture so as to add that digital representation to the patient's imagedata model.

For example, when the system of the present invention is used for kneereplacement surgery, a digital representation of a femoral resectionguide mount 20 may be added to the patient's image data model (FIGS. 1and 6). In the context of a total knee replacement, femoral resectionguide mount 20 may be formed for placement on the exposed condyles of apatient's femur to assure precise and accurate positioning of a femoralresection guide 26 which is used to direct and control bone resection offemur 5 during surgery. Although the femoral resection guide 26 can takevarious forms and configurations, the present invention will bedescribed with reference to a distal resection guide currently offeredby applicant Wright Medical Technology, Inc. (Wright Medical Part No.K001-2659). Significantly, femoral resection guide mount 20 providesthis precise and accurate positioning function without the need forother external fixtures or the use of an intramedullary stem insertedthrough the intercondylar notch and upwardly through femur 5 along thefemoral shaft axis. A digital representation of a tibial resection guidemount 22 may also be added to the patient's image data model (FIG. 6).Tibial resection guide mount 22 is similarly formed for placement on theexposed superior articular surface of a patient's tibia 6 to assureprecise and accurate positioning of a tibial resection guide 28 used todirect and control bone resection of the superior articular surface ofthe exposed tibia during surgery.

Referring to FIGS. 8-11, a femoral resection guide mount 20 according toone embodiment of the invention is formed from a resilient polymermaterial of the type that is suitable for use in connection with stereolithography, selective laser sintering, or the like manufacturingequipment. Resection guide mount 20 comprises a unitary block includinga bifurcated condylar yolk 25 and a guide receptacle 29. Bifurcated yolk25 includes a pair of spaced apart arms 30, 31 that project outwardlyfrom a base 33. Arm 30 has a lower or bone engaging surface 36 and athrough-bore 38, and arm 31 has a lower or bone engaging surface 40 anda through-bore 42. Through the previously discussed imaging operations,the bone engaging surfaces 36, 40 are configured for complementarymatching with anatomical surface features of a selected region of thepatient's natural bone. For the femoral resection guide mount 20embodiment of FIGS. 8-11, the selected bone region comprises thecondyles of the patient's femur.

Guide receptacle 29 includes a pair of wings 44,46 that projectoutwardly, in opposite directions from base 33 and in spaced relation toarms 30,31. Each wing 44, 46 includes a pylori 48 projecting upwardly tosupport guide housing 49 such that an elongate slot 52 is definedbetween base 33 and guide housing 49. Slot 52 is sized and shaped toallow a typical surgical saw, of the type often used for bone resection,to pass through from a correspondingly positioned and sized slot inresection guide 26 without contact, or with only incidental contact withresection guide locator 20. An annular wall 55, having a shape that iscomplementary to the outer profile of femoral resection guide 26,projects outwardly in substantially perpendicular relation to a backwall 61 and thereby defines a recess 58. In some preferred embodiments,recess 58 is sized so as to accept femoral resection guide 26 with a“press-fit”. By press-fit it should be understood that annular wall 55is sufficiently resilient to deflect or compress elastically so as tostore elastic energy when femoral resection guide 26 is pushed intorecess 58. Of course, it will also be understood that femoral resectionguide 26 will have an outer circumferential shape that is complementaryto the circumferential shape of recess 58, but slightly larger in size,for press-fit embodiments. Also, femoral resection guide 26 may beretained within recess 58 by only frictional engagement with annularwall 55 or, in less preferred embodiments, resection guide 26 can simplyslide into recess 58 without operative contact or only incidentalengagement with annular wall 55. First through-bores 62, 64 are definedin back wall 61 in spaced relation to one another, with a secondthrough-bore 67,69 being associated with each first through-bore 62,64.In the embodiment shown in FIGS. 8-11, the first through-bores 62, 64are large square or rectangular openings, a configuration that easesmanufacture, reduces material use, and provides sufficient space fordriving pins, wires, screws or other appropriate fasteners through aplurality of adjacent bores provided on the femoral resection guide 26.A groove 70 is defined in the outer surface of base 33 and centrallylocated with respect to recess 58 for matching to resection guide 26.

Referring to FIGS. 12-18, a tibial resection guide mount 22 according toone embodiment of the invention is formed from a resilient polymermaterial of the type that is suitable for use in connection with stereolithography, selective laser sintering, or the like manufacturingequipment, e.g., a polyamide powder repaid prototype material issuitable for use in connection with selective laser sintering. Resectionguide mount 22 comprises a unitary block including a bifurcated yolk 75and a guide receptacle 79. Bifurcated yolk 75 includes a pair of spacedapart arms 80, 81 that project outwardly from a base 83. Arm 80 has alower surface 86 and arm 81 has a lower surface 90.

Guide receptacle 79 includes a pair of wings 84, 86 that projectoutwardly, in opposite directions from base 83 and in spaced relation toarms 80,81. Each wing 84,86 includes a pylori 88 projecting upwardly tosupport guide housing 89 such that an elongate slot 94 is definedbetween base 83 and guide housing 89. Slot 94 is sized and shaped toallow a typical surgical saw, of the type often used for bone resection,to pass through from a correspondingly positioned and sized slot inresection guide 28 without contact, or with only incidental contact withresection guide locator 22. An annular wall 95, having a shape that iscomplementary to the outer profile of tibial resection guide 28,projects outwardly in substantially perpendicular relation to a backwall 101 and thereby defines a recess 108. Recess 108 is sized so as toaccept tibial resection guide 28 with a press-fit. First through-bores112, 114 are defined in back wall 101 in spaced relation to one another,with a second through-bore 117, 119 being associated with each firstthrough-bore 112, 114.

Returning to the digital image models 3 previously disclosed, andconsidering a generalized digital model of resection guide mount 20added to the patient's femur image data, the anatomic surface featuresof the patient's femur, e.g., the condylar surface topography, may becomplementarily mapped onto each of lower surface 36 and lower surface40 of arms 30, 31. It will be understood that complementary mapping ofthe digital images results in localized prominences on the surface of abone, e.g., a condyle, cortical, or articular surface, becominglocalized concavities on lower surface 36 or lower surface 40, whilelocalized concavities on the surface of a bone become localizedprominences on lower surface 36 or lower surface 40. In this way, eachof lower surface 36 and lower surface 40 is redefined with acomplementary, substantially mirror image of the anatomic surfacefeatures of a selected region of the patient's femur. As a consequenceof this complementary bone surface mapping, resection guide mount 20releasably “locks” on to the complementary topography of thecorresponding portion of the patient's natural femur, e.g., the condylarsurfaces, without the need for other external or internal guidancefixtures. In other words, the mating of bone surface asperities in theircorresponding concavities formed in conformal bone engaging surfaces offemoral resection guide mount 20 ensures that little or no relativemovement, e.g., slipping sideways, occurs between femoral resectionguide mount 20 and the condylar surface. A substantially identicalmapping is carried out in connection with the design of a patientspecific tibial resection guide mount 22.

A visual presentation of the virtual alignment results between thepatient's femur and resection guide mount 20 is created and forwarded tothe surgeon to obtain approval of the results prior to manufacturing(FIGS. 1, 19, 20). Upon receipt of the surgeon's approval, resectionguide mount 20, and in appropriate instances resection guide mount 22,is manufactured and returned to the surgeon for use in the surgery.

During a total knee replacement the present invention is used in thefollowing manner. The surgeon first orients resection guide mount 20 onfemur 5 until lower surfaces 36, 40 of resection guide mount 20 securelyengage one another so as to releasably “interlock” with the topographyof the exposed surface 4 of femur 5. With resection guide mount 20locked onto the patient's femur, a surgeon press-fits an appropriatelyconfigured Distal Resection Guide 26 (e.g. Wright Medical Technology,Inc. Part No. K001-2659) in recess 58 of resection guide mount 20. Asindicated in FIGS. 19-20, this results in the resection guide mount 20,and particularly the guide receptacle portion 29 of the resection guidemount 20, being sandwiched between the resection guide 26 and thepatient's bone. Pins are driven into through-bores of the resectionguide 26, but advantageously the pins do not come into contact with theportions of resection guide mount 20 that define through-bores 62, 64 or67, 69. These through-bores are often the most proximal on resectionguide mount 20. With resection guide mount 20 held securely in place, adrill bit is advanced into through-bores 38 and 42, through-bores 62, 64defined in back wall 61, and/or into second through-bores 67,69. It isoften preferable for the drill to protrude about 15 mm intothrough-bores 38 and 42 into the femoral bone so the drill holes will bepresent after the distal resection. Increased hole depth may benecessary in the event of a larger distal resection to correct a flexioncontracture. For additional stability, fixation pins (not shown) may beleft in through-bores 38 and 42, but must be removed prior to resection.With the resection guide mount 20 thus accurately positioned withrespect to the selected bone region and the resection guide 26-guidemount 20 construct appropriately secured to the patient's bone, thesurgeon uses a conventional surgical blade and the resection slot of theresection guide 26 to resect the patient's bone.

When the system of the present invention is used for ankle replacementsurgery, a tibial resection guide mount 120 and a talar resection guidemount 122 are formed and mounted to the patient's lower tibia 123 andupper talus 124, respectively, in much the same way as femoral resectionguide mount 20 and tibial resection guide mount 22. More particularly, atibial resection guide mount 120 according to one embodiment of theinvention is formed from a resilient polymer material of the type thatis suitable for use in connection with stereo lithography or the likemanufacturing equipment (FIG. 22). Resection guide mount 120 comprises aunitary body including a cruciform tibial yolk 125 projecting upwardlyfrom a base 127 that further defines a guide receptacle recess 129.Cruciform yolk 125 includes a pair of spaced apart arms 130, 131 thatproject outwardly from a central post 133. Arms 130, 131 and centralpost 133 each have a conformal bone engaging surface 134 that iscomplementary to the contours of a corresponding portion of thepatient's lower tibia (FIG. 26). Through the previously discussedimaging operations, conformal bone engaging surfaces 134 of arms 130,131 and central post 133 are configured for complementary matching withanatomical surface features of a selected region of the patient'snatural bone. For tibial resection guide mount 120, the selected boneregion comprises the lower surfaces of the patient's tibia.

A pilot block 135 projects outwardly from central post 133, adjacent tothe intersection of arms 130,131. A support block 136 is located on base127 in spaced relation to pilot block 135. Guide receptacle recess 129is defined by a pair of wings 144,146 extend outwardly from either sideof central post 133 in opposite directions on base 127, with supportblock 136 located between them. Each wing 144, 146 includes a pylori 148projecting outwardly from base 127 so as to provide lateral support fortibial resection guide 150 (FIGS. 21 and 22). An elongate slot 152 isdefined transversely in a central portion of base 127 below pilot block135, but above support block 136. Each wing 144, 146 also defines a slot153 that is oriented at an angle relative to central post 133. Slots 152and 153 are sized and shaped to allow a typical surgical saw 151 (FIG.26) of the type often used for bone resection, to pass through from acorrespondingly positioned and sized slot in resection guide 150 withoutcontact, or with only incidental contact with resection guide locator120.

Referring to FIGS. 21 and 23, tibial resection guide 150 includes a pairof arms 155 that project downwardly and outwardly in diverging angularrelation from the ends of a bridge beam 157. In this way, the shape oftibial resection guide 150 is complementary to the shape of guidereceptacle recess 129 as defined by the inwardly facing surfaces ofpilot block 135, support block 136, and pylons 148. Bridge beam 157defines an elongate slot 156 and arms 155 each define a slot 158 thatare, when assembled to resection guide mount 120, coextensively alignedwith elongate slot 152 and slots 153, respectively in base 127. Theinwardly facing surfaces 149 of pilot block 135, support block 136, andpylons 148, that together define guide receptacle recess 129, have ashape that is complementary to the outer profile of tibial resectionguide 150. In some preferred embodiments, guide receptacle recess 129 issized so as to accept tibial resection guide 150 with a “press-fit”. Bypress-fit it should be understood that the inwardly facing surfaces 149of pilot block 135, support block 136, and pylons 148 are sufficientlyresilient to deflect or compress elastically so as to store elasticenergy when tibial resection guide 150 is pushed into guide receptaclerecess 129. Of course, it will also be understood that tibial resectionguide 150 will have an outer peripheral shape that is complementary tothe circumferential shape of guide receptacle recess 129, but slightlylarger in size, for press-fit embodiments. Also, tibial resection guide150 may be retained within guide receptacle recess 129 by onlyfrictional engagement with the inwardly facing surfaces of pilot block135, support block 136, and pylons 148 or, in less preferredembodiments, tibial resection guide 150 can simply slide into guidereceptacle recess 129 without operative contact or only incidentalengagement with the inwardly facing surfaces of pilot block 135, supportblock 136, and pylons 148.

Referring to FIGS. 21 and 28-33, a talar resection guide mount 122according to one embodiment of the invention is formed from a resilientpolymer material of the type that is suitable for use in connection withstereo lithography, selective laser sintering, or the like manufacturingequipment, e.g., a polyamide powder repaid prototype material issuitable for use in connection with selective laser sintering. Talarresection guide mount 122 also includes a conformal bone engagingsurface 137 that is complementary to the contours of a correspondingportion of the patient's upper talus 124 (FIGS. 21, 28, and 31-34).Through the previously discussed imaging operations, conformal boneengaging surface 137 of talar resection guide mount 122 is configuredfor complementary matching with anatomical surface features of aselected region of the patient's natural bone. For talar resection guidemount 122, the selected bone region comprises the outer, upper surfacesof the patient's talus.

Talar resection guide mount 122 comprises a unitary block that defines acentral guide receptacle recess 179 and a pair of through-bores 180(FIG. 30). Guide receptacle recess 179 is defined by the inwardly facingsurfaces 181 of a pair of wings 184, 186 that project outwardly, inopposite directions from a base 183. Each wing 184,186 includes a pylori188 projecting upwardly to support guide housing 189 such that anelongate slot 194 is defined within base 183 and below guide housing 189(FIGS. 31 and 33). Slot 194 is sized and shaped to allow a typicalsurgical saw 151, of the type often used for bone resection, to passthrough from a correspondingly positioned and sized slot 196 in talarresection guide 200 without contact, or with only incidental contactwith talar resection guide locator 122. An annular wall 195, having ashape that is complementary to the outer profile of talar resectionguide 200, projects outwardly in substantially perpendicular relation toa back wall and so as to further defines guide receptacle recess 179.

Referring to FIGS. 28, 29, and 30, talar resection guide 200 includes apair of confronting, parallel plates 202, 203 that define elongate slot196 between them, and are joined to one another at their ends by wings206. In this way, the shape of talar resection guide 200 iscomplementary to the shape of guide receptacle recess 179 as defined bythe inwardly facing surfaces 181 of wings 184, 186, base 183, and pylons188. Guide receptacle recess 179 is sized so as to accept talarresection guide 200 with a press-fit. Of course, it will also beunderstood that talar resection guide 200 will have an outer peripheralshape that is complementary to the circumferential shape of guidereceptacle recess 179, but slightly larger in size, for press-fitembodiments. Also, talar resection guide 200 may be retained withinguide receptacle recess 179 by only frictional engagement with theinwardly facing surfaces 181 of wings 184, 186, base 183, and pylons 188or, in less preferred embodiments, talar resection guide 200 can simplyslide into guide receptacle recess 179 without operative contact or onlyincidental engagement with the inwardly facing surfaces 181 of wings184, 186, base 183, and pylons 188.

As with the digital image models 3 previously disclosed, and consideringa generalized digital model of a tibial resection guide mount 120 addedto the patient's lower tibia image data, the anatomic surface featuresof the patient's lower tibia, e.g., the surface topography, may becomplementarily mapped onto each of conformal bone engaging surfaces 134of arms 130, 131 and central post 133, i.e., the surfaces that willengage the bones unique surface topography. It will be understood thatcomplementary mapping of the digital images results in localizedprominences on the surface of a bone becoming localized concavities onconformal bone engaging surfaces 134 of arms 130, 131 and central post133, while localized concavities on the surface of a bone becomelocalized prominences on conformal bone engaging surfaces 134 of arms130, 131 and central post 133. In this way, each of conformal boneengaging surfaces 134 of arms 130, 131 and central post 133 is redefinedwith a complementary, substantially mirror image of the anatomic surfacefeatures of a selected region of the patient's lower tibia. As aconsequence of this complementary bone surface mapping, tibial resectionguide mount 120 releasably “locks” on to the complementary topography ofthe corresponding portion of the patient's natural tibia without theneed for other external or internal guidance fixtures. In other words,the mating of bone surface asperities in their corresponding concavitiesformed in conformal bone engaging surfaces 134 of tibial resection guidemount 120 ensures that little or no relative movement, e.g., slippingsideways, occurs between tibial resection guide mount 120 and the tibialsurface. A substantially identical mapping is carried out in connectionwith the design of a patient specific talar resection guide mount 122.

A visual presentation of the virtual alignment results between thepatient's lower tibia and resection guide mount 120, as well as, thepatients upper talus and resection guide mount 122 are created andforwarded to the surgeon to obtain approval of the results prior tomanufacturing. Upon receipt of the surgeon's approval, resection guidemount 120 and resection guide mount 122, are manufactured and returnedto the surgeon for use in the surgery.

During a total ankle replacement, the present invention is used in thefollowing manner. The surgeon first orients resection guide mount 120 onlower tibia 123 until the conformal bone engaging surfaces 134 of arms130, 131 and central post 133 of resection guide mount 120 securelyengage one another so as to releasably “interlock” with the topographyof the exposed surface of lower tibia 123. With resection guide mount120 locked onto the patient's lower tibia, a surgeon press-fits anappropriately configured distal resection guide 150 in guide receptaclerecess 129 of resection guide mount 120. This results in the resectionguide mount 120 being sandwiched between the resection guide 150 and thepatient's bone (FIGS. 21, 24, and 25). With the resection guide mount120 accurately positioned with respect to the selected bone region andresection guide 150-guide mount 120 construct appropriately secured tothe patient's bone by virtue of the mating of bone surface asperities intheir corresponding concavities formed in conformal bone engagingsurfaces 134, the surgeon uses a conventional surgical blade 151 and theresection slots 152 and 153 of resection guide 150 to resect thepatient's bone (FIG. 27).

In a similar fashion, when talar resection guide mount 122 is added tothe patient's talar image data, the anatomic surface features of thepatient's upper talus, e.g., the surface topography, may becomplementarily mapped onto conformal bone engaging surface 137. It willagain be understood that complementary mapping of the digital imagesresults in localized prominences on the surface of a bone becominglocalized concavities on conformal bone engaging surface 137, whilelocalized concavities on the surface of a bone become localizedprominences on conformal bone engaging surface 137. In this way,conformal bone engaging surface 137 is redefined with a complementary,substantially mirror image of the anatomic surface features of aselected region of the patient's lower tibia. As a consequence of thiscomplementary bone surface mapping, talar resection guide mount 122releasably “locks” on to the complementary topography of thecorresponding portion of the patient's natural talus without the needfor other external or internal guidance fixtures.

To continue the total ankle replacement the surgeon first orientsresection guide mount 122 on upper talus 124 until conformal boneengaging surface 137 of resection guide mount 122 “locks” to thetopography of the exposed surface of upper talus 124. With resectionguide mount 122 locked onto the patient's upper talus, a surgeonpress-fits an appropriately configured distal resection guide 200 inguide receptacle recess 179 of resection guide mount 122. This resultsin resection guide mount 122 being sandwiched between resection guide200 and the patient's bone (FIGS. 21, 28, 32, and 33). With theresection guide mount 122 accurately positioned with respect to theselected bone region and resection guide 200-guide mount 122 constructappropriately secured to the patient's bone, by virtue of the mating ofbone surface asperities in their corresponding concavities formed inconformal bone engaging surfaces 137, the surgeon uses a conventionalsurgical blade 151 and the resection slot 196 of resection guide 200 toresect the patient's bone (FIG. 34).

It is to be understood that the present invention is by no means limitedonly to the particular constructions herein disclosed and shown in thedrawings, but also comprises any modifications or equivalents within thescope of the claims.

What is claimed is:
 1. A surgical instrument comprising: a resectionguide defining an elongate slot and a first pair of through holes; and aresection guide locator having a body including as bone engagementportion having a surface that is complementary to said surfacetopography of said hone to be resected; the body defining a socket sizedto receive the resection guide so as to maintain said resection guide inposition while said surface of said bone engagement portion is arrangedin contacting relation with the bone, the body of the resection guidelocator defining an elongate slot and a second pair of through holeswithin the socket that extend through the bone engagement portion,wherein the elongate slot and second pair of through holes defined bythe resection guide locator are positioned within the socket such thatthe elongate slot and second pair of through holes defined by theresection guide locator align with the elongate slot and the first pairof through holes defined by the resection guide when the resection guideis received within the socket, and wherein the elongate slot defined bythe resection guide locator does not intersect either of the second pairof through holes defined by resection guide locator.
 2. A surgicalinstrument according to claim 1 wherein said surface of said boneengagement portion comprises a surface topography wherein one or morelocalized prominences have a location, shape, and size that complementthe location, shape, and size of a corresponding one or more localizedconcavities that define a portion of said surface topography of saidhone.
 3. A surgical instrument according to claim 1 wherein said surfaceof said bone engagement portion comprises a surface topography whereinone or more localized concavities have a location, shape, and size thatcomplement the location, shape, and size of a corresponding one or morelocalized prominences that define a portion of said surface topographyof said hone.
 4. A surgical instrument according to claim 2 or 3 whereinsaid surface of said bone comprises a condylar surface.
 5. A surgicalinstrument according to claim 2 or 3 wherein said surface of said bonecomprises an articular surface.
 6. A surgical instrument according toclaim 2 or 3 wherein said surface of said bone comprises a corticalsurface.
 7. A surgical instrument according to claim 1 wherein saidsurface of said bone engagement portion comprises a complementary,substantially mirror image of the anatomic surface features of aselected region of said bone.
 8. A surgical instrument according toclaims 2 or 3 wherein said one or more localized prominences and saidone or more corresponding localized concavities securely engage oneanother so as to releasably interlock said surface of said boneengagement portion of said resection guide locator with said surface ofsaid bone.
 9. A surgical instrument according to claim 2 or 3 whereinmating of at least one of said bone surface prominences with acorresponding complementary concavity defined in a bone engaging surfaceof said resection guide locator impedes relative movement therebetween.10. A surgical instrument according to claim 2 or 3 wherein mating of atleast one of said bone surface concavity with a correspondingcomplementary prominence defined in a bone engaging surface of saidresection guide locator impedes relative movement therebetween.
 11. Asurgical instrument comprising; resection guide defining an elongateslot and a first pair of through holes; and a resection guide locator,including a bone engagement portion having a surface that iscomplementary to said surface topography of said bone to be resected;and a socket defined by a resilient wall arranged for storing energywhen the resection guide is press-fit in said socket and operativelyengages a portion of said wall so as to maintain said resection guide inposition while said surface of said bone engagement portion is arrangedin contacting relation with the bone, wherein the bone engagementportion of the resection guide locator defines an elongate slot and asecond pair of through holes that are positioned relative to the socketdefined by the resection guide locator such that the elongate slot andthe second pair of through holes defined by the resection guide locatoralign with the elongate slot and the first pair of through holes definedby the resection guide when the resection guide is received within thesocket, the elongate slots defined by the resection guide and theresection guide locator being sized and configured to receive a sawblade when the bone engagement portion is in contact with a bone and theresection guide is received within the socket defined by the resectionguide locator, and wherein the elongate slot defined by the resectionguide locator does not intersect either of the second pair of throughholes defined by the resection guide locator.
 12. A surgical instrumentaccording to claim 11 wherein said surface of said bone engagementportion comprises a surface topography wherein one or more localizedprominences have a location, shape, and size that complement thelocation, shape, and size of a corresponding one or more localizedconcavities that define a portion of said surface topography of saidbone, and further wherein said surface of said bone engagement portioncomprises a surface topography wherein one or more localized concavitieshave a location, shape, and size that complement the location, shape,and size of a corresponding one or more localized prominences thatdefine a portion of said surface topography of said bone.
 13. A surgicalinstrument according to claim 11 wherein said surface of said bonecomprises at least one of a condylar surface, an articular surface, anda cortical surface.
 14. A surgical instrument according to claim 11wherein said surface of said bone engagement portion comprises acomplementary, substantially mirror image of the anatomic surfacefeatures of a selected region of said bone.
 15. A surgical instrumentaccording to claim 12 wherein said one or more localized prominences andsaid one or more corresponding localized concavities securely engage oneanother so as to releasably interlock said surface of said boneengagement portion of said resection guide locator with said surface ofsaid bone.
 16. A surgical instrument according to claim 12 whereinmating of at least one of said bone surface prominences with acorresponding complementary concavity defined in a bone engaging surfaceof said resection guide locator impedes relative movement therebetween.17. A surgical instrument according to claim 12 wherein mating of atleast one of said bone surface concavity with a correspondingcomplementary prominence defined in a bone engaging surface of saidresection guide locator impedes relative movement therebetween.
 18. Asurgical instrument comprising: a resection guide defining an elongateslot and a first pair of holes; and a resection guide locator, includinga body having a bone engagement portion having a surface that iscomplementary to the surface topography of said bone to be resected, thebody defining a socket and an elongate slot and a second pair of holes,the socket sized to receive by press-fit the resection guide so as tomaintain sand resection guide in a substantially fixed orientationrelative to the bone engagement portion while said surface of said boneengagement portion is arranged in secure interlocking relation with saidbone surface, wherein the elongate slot and second pair of holes arepositioned relative to the socket such that the elongate slot and secondpair of holes of the resection guide locator align with elongate slotand the first pair of holes defined by the resection guide when theresection guide is received within the socket defined by the resectionguide locator, the elongate slots defined by the resection guide and theresection guide locator being sized and configured to receive a sawblade when the bone engagement portion is in contact with a bone and theresection guide is received within the socket defined by the resectionguide locator, and wherein the elongate slot defined by the resectionguide locator does not intersect either of the second pair of throughholes defined by the resection guide locator.
 19. A surgical instrumentaccording to claim 18 wherein said surface of said bone engagementportion comprises a surface topography wherein one or more localizedprominences have a location, shape, and size that complement thelocation, shape, and size of a corresponding one or more localizedconcavities that define a portion of said surface topography of saidbone, and further wherein said surface of said bone engagement portioncomprises a surface topography wherein one or more localized concavitieshave a location, shape, and size that complement the location, shape,and size of a corresponding one or more localized prominences thatdefine a portion of said surface topography of said bone.
 20. A surgicalinstrument according to claim 18 wherein said surface of said bonecomprises at least one of a condylar surface, an articular surface, anda cortical surface.
 21. A surgical instrument according to claim 18wherein said surface of said bone engagement portion comprises acomplementary, substantially mirror image of the anatomic surfacefeatures of a selected region of said bone.
 22. A surgical instrumentaccording to claim 19 wherein said one or more localized prominences andsaid one or more corresponding localized concavities securely engage oneanother so as to releasably interlock said surface of said boneengagement portion of said resection guide locator with said surface ofsaid bone.
 23. A surgical instrument according to claim 19 whereinmating of at least one of said bone surface prominences with acorresponding complementary concavity defined in a bone engaging surfaceof said resection guide locator impedes relative movement therebetween.24. A surgical instrument according to claim 19 wherein mating of atleast one of said bone surface concavity with a correspondingcomplementary prominence defined in a one engaging surface of saidresection guide locator impedes relative movement therebetween.